1. Field of the Invention
The present invention relates to a pelletizer which is particularly adapted to be mounted to the end of an extruder for cutting streams of plastic extruded through a die into pellets which are carried away by water flow in a chamber where the cutting takes place.
2. Description of the Prior Art
Extruders for extruding plastic material into a molten stream of plastic material have been known and used for some time. One particular use of such an extruder is in connection with a pelletizer assembly which is mounted to the end of the extruder. In such a combination of an extruder and a pelletizer, a die having a plurality of holes therein is mounted at the end of the extruder and at the entrance to the pelletizer assembly and forms part of both. The pelletizer then includes a rotating cutter assembly having cutting blades positioned adjacent the die face from which streams of molten plastic material flow. The rotating cutter assembly cuts the streams of plastic material into pellets of various sizes depending upon the extrusion flow rate through the holes in the die and the speed of rotation of the cutter assembly.
Also, the flow of water through the chamber serves to carry the pellets away from the chamber.
In such a combined extruder and pelletizer assembly it is desirable to provide means for facilitating a smooth flow of the plastic material from the extruder to the die holes in the die. Also it is desirable to provide means for gaining easy access to the chamber for replacing worn cutting blades of the cutter assembly and to generally observe the formation of pellets by the rotating cutter assembly.
It is also desirable to provide a long useful life for the knife blades of the cutter assembly. That it to say, it is desirable to provide knife blades which will last a long time. In addition, it is desirable to provide some means for automatically readjusting the position of the cutter assembly adjacent the die face as the space between the cutter assembly and the die face increases due to wear of the knife blades. In this respect, it is desirable to keep the knife blades juxtaposed to the die face to ensure clean cutting of the streams of plastic material into pellets.
As will be described in greater detail hereinafter, the pelletizer of the present invention provides a position control assembly for controlling the position of the cutter assembly adjacent the die face.
Additionally, the pelletizer of the present invention provides a knife blade design and configuration which enhances the cutting action of the knife blade and provides a longer useful life of the knife blade.
Also, the pelletizer of the present invention as will be described in greater detail hereinafter provides means for observing the cutting action in the cutting chamber of the pelletizer and for enabling one to gain quick access to the interior of the chamber.
Still further, the present invention provides a die assembly construction which facilitates the flow of molten plastic material from the extruder to the holes in the die.
These advantageous features of the pelletizer of the present invention and the manner in which they are constructed and incorporated in the pelletizer and the manner in which they function will be described in greater detail below in connection with the description of the preferred embodiments of the invention.